A conventional SR flip-flop has been made by the circuit of a feedback device using three terminal two active devices. As a result, the device has complexity circuit structure and its operation speed cannot be reduced. To settle these problems,the SR flip-flop of the present invention is constructed by the bistable circuit using the device, which is disclosed in U.S. Pat. No. 5,229,636 or JP PATENT DOCUMENT 5-60270.